Field of the Invention
The present invention relates to an image capturing apparatus that uses an image sensor typified by a CMOS image sensor, and a method for controlling the image capturing apparatus.
Description of the Related Art
An increasing number of recent electronic cameras and video cameras include a CMOS image sensing device mounted thereon. A commonly used CMOS image sensing device employs a scheme in which signal charges generated and accumulated in photoelectric conversion units of pixels arranged in a two-dimensional matrix are sequentially read out on a row-by-row basis. In recent years, a simultaneous image capturing function (global shutter function) of accumulating signal charges at the same timing has been proposed, and the applications of a CMOS image sensing element having the global shutter function are also increasing.
According to Japanese Patent Laid-Open No. 2011-217315, a plurality of CCDs serving as charge holding units arranged in series are provided in each pixel, and the dynamic range is expanded by obtaining signals with different accumulation periods of time. However, the provision of a plurality of CCDs in a single pixel in a solid-state image capturing apparatus including an increasing number of pixels results in a reduction in size of the photodiode portion serving as a photoelectric conversion unit, and thus may reduce the sensitivity.
According to Japanese Patent Laid-Open No. 2011-217315, the output from the sensor is performed for one row at a time even though the global shutter is used, and therefore, it takes a long readout period of time to obtain signals with different accumulation periods of time. Furthermore, according to Japanese Patent Laid-Open No. 2011-217315, the charge holding portion is disposed in each of the pixels of a first chip, and therefore, the size of the photodiode portion is equivalent to that of the conventional counterpart.